I am thinking that its bugged. According to a video I watched, after being harpooned it should be ripped apart. Ive changed the difficulty to casual and even after harpooning it 4+times its not being ripped apart yet in the walkthrough video it happens the first time.

So is there any chance to clear this chapter without bug, cause ive got the same problem, spider wont die?

So its not just me! Hahaha, its gotta be a bug

Are you pressing F or B on the control panel to pull it apart? I am and it doesn't get pulled apart it just releases and comes after me again, I've killed its tentacles over and over and the three yellow orbs from his mouth (they dont even regrow for me, the ones in its mouth that is, the three on top keep regrowing but he wont die even after he gets trapped by the harpoons and I press the button over and over)

Are you pressing F or B on the control panel to pull it apart? I am and it doesn't get pulled apart it just releases and comes after me again, I've killed its tentacles over and over and the three yellow orbs from his mouth (they dont even regrow for me, the ones in its mouth that is, the three on top keep regrowing but he wont die even after he gets trapped by the harpoons and I press the button over and over)

i restart chapter and finally kill busterd, fisrt killed his face, after that active the harpoons and pressing all the time 'F' , try to restart lvl, good luck